Recent years have seen developments in video distribution services with an increase in the speed of Internet access lines, the emergence of their optical version, and increases in the capacities of the backbones of carriers and Internet service providers (ISPs). ISPs and carriers regard video distribution services as services for differentiating themselves from others as well, and prepare contents with unique features to obtain users.
Further, coding techniques have made progress to allow video signals, which basically contain a large amount of information, to be compressed while maintaining their video quality, which may be considered as another factor in the increase in these video services. Standards such as MPEG-2, MPEG-4, and H.264 have made it possible to transmit video signals in a relatively low frequency band of several Mbps to tens of Mbps, which has enabled simultaneous distribution of video to multiple users.
Further, studies have been made of future IP redistribution of broadcast services that distributes present broadcast services of terrestrial digital broadcasting through IP networks. Thus, video services are expected to become one of basic network services in the future.